Hollow grate-bar



J. M. IIoPwouq HOLLOW (sR'IfiE BAR.

APPLICATION FILED. OCT. 9', I917.

Patented Feb. 10, 1920.

2 SHEETS-SHEET I.

WITNESSES 7 H 8 7 3 I I 3 8 I I I II IIIII IIII I] IIII/I I I I \I I INVENTOR l I I I I I Patented Feb. 10, 1920.

2 SHEETS-SHEET 2.

INVENTOR FIEiE.

WITNESSES k to UNITED STATES. PATENT OFFICE.

JOHN M. HOPWOOD, OF DORMONT, PENNSYLVANIA, ASSIGNOR 'IO DARWIN S. WOLCOTT, TRUSTEE, 0F SEWICKLEY, PENNSYLVANIA.

HOLLOW GRATE-BAR.

Specification of Letters Patent.

Application filed October 9, 1917. Serial No. 195,527.

To all whom it may concern:

Be it known that I, JOHN M. Horwooo, residing at Dormont, in the county of Allegheny and State of Pennsylvania, a citizen of the United States, have invented or discovered certain new and useful Improvements in Hollow Grate-Bars, of which improvement the following is a specification.

The invention described herein relates to the introduction of air below fuel supporting members and its discharge through between such members and its distribution in such manner as to insure practically uniform combustion at all points of the bed of fuel. The invention is hereinafter. more fully described and claimed.

In the accompanying drawings forming a part of this specification, Figure 1 is a sectional plan view of a boiler fire-box on a horizontal plane above the grate bars; Figs. 2 and 3 are vertical sections on planes indicated respectively, by-the lines II-II and III-III, Fig. 1; Fig. 4 is a view similar to Fig. 2, illustrating a modification of the improvement; Fig. 5 is a sectional detall view illustrating a modification of the construction of the grate bars; Fig. 6 shows transverse sections of the grate bars, of a.

modified form or construction of bar.

In the practice of the invention, the grate bars 1, the construction of which will be hereinafter described, extend from the fuel charging or front end of the furnace toward the, rear end thereof and are supported in an inclined position by flanges 2 at opposite ends of the wind box 3, and by vertical wall 4 extending across the box as clearly shown in Figs. 1 and 2. The box 3 is preferably made of metal and of such horizontal dimensionsas to completely fill the fire box or furnace chamber except at the rear end thereof, where a sufficient space is provided for the dump plate on to which the ashes are discharged from the rear ends of the grate bars. The grate bars are made hollow and are provided at or near their middle portions with openings 5, arranged on opposite sides of the transverse wall 6. In the construction shown in Figs. 1, 2 and 3, these openings serve as inlets so that air entering the respective openings will flow to opposite connecting with such channel.

ends of the grate bars and escape through outlets 7 into chambers 8 in the wind box. In the constructions shown in Figs. 1, 2, and 3, air is supplied to passages in the grate bars through the channel 9 formed between the transverse partitions) 4:, the openings 5 This channel 1s connected at one or both ends to flues '10, for conducting air under pressure from by a suitable reciprocation of the grate bars or by any other suitable means. When the movement of the fuel is to be effected by reciprocating the grate bars, the movable bars are merely supported by the flanges 2 and the walls while the alternate bars are held from movement by any suitable means, as for example, by lugs 14 projecting into holes in the front flange 2. The reciprocating bars may be connected to their operating mechanism through the lugs 15 as shown in Fig. 5 or by any other suitable device.

' The fuel will naturally bank' up on the front ends of the grate bars and will diminish in depths .toward the rear of the grate bars, and hence there will be a greater generation of gases at the front of the fire boxthan at other points, due not only to' the heating of the reen fuel, but also to the larger mass of fue on the front portions of the grate bars. This generation of large quantities of gases at the front} of the fire box necessitates the feeding'of larger quanti- 1 ties of air at that point to insure thorough combustion, and hence it is preferred to perforate the walls of the front portions of the grate bars as shown at 16 so that jets of air may be forced direct from the passages in the grate bars to the banked up fuel.

In case air in sufficient quantity to effect the desired combustion at the front of the fire box cannot be supplied through the perforations 16, an auxiliary 'air chamber 17 may be arranged above the neck 12, the wall of such chamber against which the fuel will be banked, being perforated as shown in Fig. 2. This chamber 17 has inlet openings 18 at one or both ends, connected to a suitable source of air under pressure.

If desired, the upper surfaces of the reciprocating grate bars may be stepped as shown in Fig. 5, so as to impart a positive push on the fuel. When employing this stepped construction, perforations may be formed through the shoulders 19 for the escape of air into the superincumbent fuel. As shown in Fig. 5, the grate bars may be made in sections adapted to be connected by bolts when in use, thereby enabling the renewal of burnt out portions of the bars.

In some casesit is desirable to reverse the directionoof flow of air through the grate bars and in such cases the wind box 3 is provided at its ends with conduits 20 adapted to be connected to a suitable source of supply of air under pressure. The walls at the upper ends of these passages are constructed to form supports for the ends of the bars permitting of the reciprocation without moving the openings 7 into the passages through the bars out of register with the conduits 20. The air under pressure, the flow of which is regulated by dampers 21, flows through passages 20 and inlet ports 7 into and along the passagesin the grate bars and through ports 5 into the chambers 8 in the wind-box. The air under pressure flows from the chambers up between the spaced bars and throu h the-superincumbent bed of fuel. By suitably shifting the dampers controlling the flow of air into the bars, the quantity and pressure of air supplied to the upper and lower portions of the fuel bed can be adjusted as desired. i

It is characteristic of the invention described herein that provision is made for distribution of the air supplied for maintaining combustion in different parts of the fuel bed as conditions, a. a, rate of combustion and thickness offuel bed, may require.

I claim herein as my invention: I

1. In a stoking mechanism the combination of a fire box, spaced grate bars arranged in the fire box parallel with the direction of movement of fuel, each of a plurality of the bars having independent longitudinal passages, each passage having an inlet and an outlet port, independent wind boxes arranged under the grate bars, the outlet ports of eachof the grate bars being connected to the respective boxes, means for connecting the inlet ports of the bars to a source of air supply, and means for regulating the pressure of air in the respective wind boxes,

and means controlling the flow of air whereby the pressure of air supplied to different portions of the fuel bed may be regu lated in accordance with the depth of fuel on such portions.

2. In a stoking mechanism the combina tion of spaced fuel supporting members, each of a plurality of said members having passages extending longitudinally thereof, each of said passages having an inlet and an outlet port, means for forclng air through said passages, means for conducting air from the outlet ports of the passages of each bar to the spaces between adjacent fuel supporting members and means for varying the pressure of the air delivered at different points of the spaces between the fuel supporting members.

3. In a stoking mechanism, the combination of a wind box having independent chambers, spaced grate bars arranged above the wind box and havin non-connected longitudinal passages therem, each of said passages having inlet and outlet ports, the out-. let ports being adapted to discharge into the respective chambers of the wind box, means for connecting the inlet ports of the grate bars to a source of. supply under pressure through the inlet ports.

4. In a stoking mechanism, the combination of a wind box, spaced partitions extending across the wind box and dividing the same into independent chambers and forming between them achannel adapted to be connected to a source of supply of air under pressure spaced grate bars arranged above the wind box and having independent longitudinal passages therein, ports connecting the passages in the grate bars to the supply channel, outlet ports adapted'to discharge from the passages in the bars into the respective chambers of the wind box, and valves controlling the flow of the air throu h the rate bars.

5. n a sto ing mechanism, the combination of a wind box, having independent chambers therein, spaced grate bars extending across the wind box and having independent longitudinal passages, each passage havlng an inlet port adapted to be connected to a source of supply of air under pressure, ports adjacent to the ends of the bars connecting the passages in the bars with the chambers in the wind box, valves controlling the flow of air through the grate bars, 4

supply of air under pressure, ports eonnectwind box arranged above the fuel opening ing the passages in the bars to the respecinto the furnace, and having perforations tive chambers in the wind box, the front for directing jets of air into fuel lying on 10 ends of the bars having perforations for the front portions of the grate hare.

directing jets of air into the fuel lying on .In testimony whereof I have hereunto set the bars, valves controlling the fiow of air my hand.

through the grate bars, and an auxiliary 4 JOHN M HOPWOOD. 

